Like other Americans, small business owners worry about crime major crime, of course, but petty crime, too. For retailers, the biggest crime worry is shoplifting.

While each individual act of shoplifting might be thought of as a petty crime, shoplifting overall is not. Retail store trade officials estimate that an act of shoplifting takes place once every five seconds somewhere in the country and ultimately costs each American about $150 a year because retailers figure their shoplifting costs in setting prices.Few retail stores in this country are immune to shoplifting.

What does a shoplifter look like?

As Addison H. Verrill of Dale System, Inc., in Garden City, N.Y., has written in a Small Business Administration management aid publication, shoplifters look like you or me. Verrill says "shoplifters can be male or female, any race or color, as young as 5 or as old as 80. Anyone who deliberately takes merchandise from a store without paying for it is a shoplifter, whether the theft is large or small, premeditated or impulsive."

About 50 percent of shoplifting reportedly is done by children, who often steal on a dare or just for kicks. Shoplifting also is carried out by "impulse lifters," who steal when an unexpected chance presents itself, by professionals and by alcoholics, kleptomaniacs and drug addicts who have a "need" to steal.

The pros, according to trade officials, are the hardest to spot. They are skilled at their thievery and, for the most part, lift items easily sold. The pros tend to concentrate on TV sets, stereos and small appliances; some pros specialize in clothing.

Verrill says a small retailer's time and money are better spent in preventing shoplifting than prosecuting it. He lists three major areas where deterrence can pay off:

Sales staffs should be trained to be on the lookout for customers carrying unusually large bags and walking with short or unnatural steps (they may be hiding items between their legs). Items carried in and out of dressing rooms should be counted. Shoplifters often handle a lot of merchandise and seem to take a long time making a decision all the while stuffing items under their clothing or into bags.

Store layouts can be arranged to deter shoplifters. Lighting should be adequate in all departments. Small items (appliances, film, watches) should be kept behind the counter or in locked cases. Noise alarms should be attached to unlocked exits.

Large retailers can hire protective personnel and buy protective equipment, including two-way mirrors, closed-circuit TV and convex wall mirrors.

A tricky question for the small retailer is when to nab a suspected shoplifter and accuse him or her of a crime. Unless the owner can make the charge stick in court, he or she is subject to countercharges of false arrest.

Thus a store owner must be sure to have actually seen the shoplifter take or conceal merchandise, must be able to identify the merchandise as the store's own and must be able to testify in court that the merchandise was not paid for and that the item was being held with intent to steal.